The present invention relates to the storage and access of electronic system identification information. Specifically, the present invention relates to the storage and retrieval of analog identification information in electronic systems having replaceable modular components.
Modular systems, in which various components may be individually added, removed, or replaced, have revolutionized the design of electronic systems. This is nowhere more apparent than in data storage devices such as RAID systems, where the storage and control components associated with the arrays of independent disks can be installed, eliminated, or upgraded virtually at will.
With the variable combinations of components in such systems, it is often desirable to provide some mechanism for electronically identifying the component within the system. Information such as serial number, location identification, hardware revision, or component date of manufacture may be useful in integrating the component into the system as a whole. Typically, this kind of information has been handled by reading a set of binary strapped connector pins, as shown in FIG. 1. In this approach, binary identification information stored in a module M1 is transmitted to a digital latch D via strapped connector pins C. It is also known to use active programmed memory devices communicating in serial or parallel, as shown in FIG. 2. In this arrangement, identification is stored in a module M2 in a memory device such as a serial E2PROM S, and shared with the system microprocessor S.
Unfortunately, these known information storage systems have potentially serious drawbacks. For example, if the information is stored as a binary number, the pin count required to transmit the information through a connector may not be tolerable. The use of a programmed memory device, even when available, complicates the manufacture of a component, and the possibility of data corruption may affect its reliability.
It can thus be seen that the need exists for a simple, inexpensive, and reliable way to store and retrieve identification information in modular systems.
An analog information storage arrangement is provided in an electronic system including at least one replaceable module. At least one analog electrical identification component installed in a module. The electrical component has an electrically readable property set to a predetermined value corresponding to identification information. An analog-to-digital converter is electrically connected to the at least one analog electrical identification component. The analog-to-digital converter is adapted and constructed to read the electrically readable property as an analog value and produce a digital identifier, such as a binary number.
The electrical identification component can be provided as a simple electrical component, such as a resistor or a capacitor. The analog-to-digital converter can be adapted to compare the read electrical property to a reference value.
In an embodiment, the analog information storage arrangement includes an impedance device, operatively connected to a module, for providing an impedance value corresponding to encoded information. A decoding device is operatively connected to the impedance device. The decoding device reads the impedance value of the impedance device.
The impedance device can be provided as an encoded resistor and reference resistor. The decoding device can include a comparator for comparing the read impedance value to a reference impedance value, which can be a resistance read from the reference resistor of the impedance device.
Alternatively, the impedance device can be provided as an encoded capacitor and reference capacitor.
The decoding device can be provided as an analog-to-digital converter, such as an 8-bit or 24-bit analog-to-digital converter. The encoded information can be selected from a group consisting of serial number, location, hardware revision, and date of manufacture.
A method of storing and retrieving analog information in an electronic system including at least one replaceable module is also set forth. The method includes the step of providing, in a module, an electrical component containing an impedance value corresponding to encoded information. Next, the impedance value of the impedance is read and assigning an identification value.
The features of the invention believed to be patentable are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings.